Automotive air conditioning systems are well known in the prior art. The operation of such automobile air conditioning systems is normally controlled by a control device in accordance with the change of temperature in the passenger compartment of an automobile. Such air conditioning systems include a compressor provided with temperature compensation means to compensate for temperature changes in an automobile compartment. The control device of prior art automobile air conditioning systems controls the magnetic clutch of the compressor and a temperature compensation means to compensate for the actual temperature in the compartment in accordance with a predetermined desired temperature.
Typically, the automobile engine is used to drive the compressor of the automobile air conditioning system. Driving this compressor places a large load on the engine which increases engine strain and reduces the energy efficiency of the engine. This reduced energy efficiency obviously results in increased fuel consumption and decreased fuel efficiency. It is, therefore, desirable to reduce the load placed on the engine while still maintaining a comfortable temperature in the automobile compartment.
When the automobile is accelerated, a large load is imposed on the automobile engine. If an automobile is being accelerated while the compressor of the automobile air conditioning system is being driven by the engine, an even greater load is imposed on the engine. Prior art control devices have been provided with a sensor to detect the acceleration of an automobile and to control the operation of compressor in accordance therewith. That is, the operation of the compressor is stopped when it is detected that the automobile is being accelerated. However, since the control device terminates the operation of the compressor, the temperature in the compartment will remain at an undesired level until acceleration of the automobile is no longer detected. In city traffic, for example, a car may often accelerate and decelerate thereby causing the compressor to remain off very frequently.
The prior art attempts to reduce the load imposed on an automobile engine due to simultaneous acceleration of the automobile and operation of an automobile air conditioning compressor which is driven by that engine. However, since the prior art solution to this entails terminating the operation of the compressor and air conditioning system, the prior art fails to effectively solve the real problem, that is, controlling the temperature of the automobile compartment to be within a predetermined range.